	US 11,719,560 B2
	Method and apparatus for optical sensing
Mahmoud Farhadiroushan, Elstree Hertfordshire (GB); Tom Parker, Elstree Hertfordshire (GB); and Sergey Shatalin, Elstree Hertfordshire (GB)
Assigned to Silixa Ltd., Elstree (GB)
Filed by Silixa Ltd., Elstree-Hertfordshire (GB)
Filed on Jul. 21, 2020, as Appl. No. 16/934,189.
Application 16/934,189 is a continuation of application No. 15/555,628, granted, now 10,883,861, previously published as PCT/GB2016/050625, filed on Mar. 7, 2016.
Claims priority of application No. 1503861 (GB), filed on Mar. 6, 2015.
Prior Publication US 2020/0386583 A1, Dec. 10, 2020
This patent is subject to a terminal disclaimer.
Int. Cl. G01D 5/353 (2006.01); G01H 9/00 (2006.01); E21B 47/135 (2012.01); G01V 8/16 (2006.01)

CPC G01D 5/3537 (2013.01) [G01D 5/35306 (2013.01); G01D 5/35374 (2013.01); G01H 9/004 (2013.01); E21B 47/135 (2020.05); G01V 8/16 (2013.01)]

9 Claims

1. An optical fiber distributed sensor system, comprising:

an optical source arranged in use to produce optical signal pulses;

an optical fiber deployable in use in an environment to be sensed and arranged in use to receive the optical signal pulses; and

sensing apparatus arranged in use to detect light from the optical signal pulses reflected back along the optical fiber and to determine any one or more of an acoustic, vibration, or temperature parameter that perturbs the path length of the optical fiber in dependence on the reflected light;

the system being characterized in that the optical fiber comprises a plurality of reflector portions distributed along its length in at least a first sensing region thereof, the reflectivity of the reflector portions being:

i) inversely dependent on the number of reflector portions in the at least first sensing region; and

ii) dependent on a selected amount of crosstalk between the reflector portions in the at least first sensing region;

wherein a product of the number of reflector portions and the average reflectivity of the reflector portions is 0.1 or less.